flex speed

[Bob Friesenhahn]

This naturally brings up the subject: Has anyone profiled bogofilter
using a profiling tool like 'gcc -pg' and 'gprof'?

Experience with software that I maintain is that a profiler often
reveals unexpected behavior which produces correct results, but not
very efficiently.  Relatively minor changes to the code can sometimes
result in a big win in terms of performance.

This bit of code in configure.ac can help make it more convenient to
use the various profiling tools:

# Enable prof-based profiling support
AC_ARG_ENABLE(prof,
	      [  --enable-prof           enable 'prof' profiling support (default disabled)],
	      [with_prof=$enableval],
	      [with_prof='no'])

# Enable gprof-based profiling support
AC_ARG_ENABLE(gprof,
	      [  --enable-gprof          enable 'gprof' profiling support (default disabled)],
	      [with_gprof=$enableval],
	      [with_gprof='no'])

# Enable gcov-based profiling support
AC_ARG_ENABLE(gcov,
	      [  --enable-gcov           enable 'gcov' profiling support (default disabled)],
	      [with_gcov=$enableval],
	      [with_gcov='no'])

.
.
.

# Add '-p' if prof source profiling support enabled
if test "$with_prof" = 'yes'
then
  CFLAGS="-p $CFLAGS"
  CXXFLAGS="-p $CXXFLAGS"
  LDFLAGS="-p $LDFLAGS"
fi

# Add '-pg' if gprof source profiling support enabled
if test "$with_gprof" = 'yes'
then
  CFLAGS="-pg $CFLAGS"
  CXXFLAGS="-pg $CXXFLAGS"
  LDFLAGS="-pg $LDFLAGS"
fi

# Add '-ftest-coverage -fprofile-arcs' if gcov source profiling
support enabled
# This is a gcc-specific feature
if test "$with_gcov" = 'yes'
then
  CFLAGS="-ftest-coverage -fprofile-arcs  $CFLAGS"
  CXXFLAGS="-ftest-coverage -fprofile-arcs  $CXXFLAGS"
  LDFLAGS="-ftest-coverage -fprofile-arcs $LDFLAGS"
fi

I have a script which converts the output of 'gprof' into a graph
description for use with 'dot' to produce a very pretty weighted
call-graph.

Bob
======================================
Bob Friesenhahn
bfriesen at simple.dallas.tx.us
http://www.simplesystems.org/users/bfriesen